Coaxial reed relay for interrupting the center conductor and simultaneously terminating its opened ends



FIELD OR INTERRUPTING THE A ril 23, 1963 c. 1.. SCHOLE 0 COAXIAL REED RELAY E CENTER CONDUCTOR AND SIMULTANEOUSLY TERMINATING ITS OPENED ENDS Filed July 13, 1961 m 9 E M 0 A 7 y 2K 5 6 l 1 z E V v B u w. a 5 C0 I A r w M 0 a A M H P 0 0 X Z 6 MW 00 P r -2? 1 m w l I l P 2 a 2 E 4 l 2 [r7 vent-or: C/ffford L. Scho/ef/e/d,

H/S Agent.

United States Patent U 3,037,125 COAXlAL REED RELAY FOR INTERRUPTING THE CENTER CONDUCTOR AND SIMULTANEOUSLY TERMINATING ITS OPENED ENDS Clifiord L. Scholefield, Greene, N.Y., assignor to General Electric Company, a corporation of New York Filed July 13, 1961, Ser. No. 123,882 1 Claim. (Cl. 333-7) This invention pertains, in general, to switching devices; and, in particular, to electromagnetically controlled switches, or relays, useful for switching electrical energy containing high frequency components, such as radio frequency and video frequency signals, in coaxial cable transmission lines.

Many presently used switches and relays are not entirely adequate for switching high frequency electrical energy in coaxial transmission lines for, among others, the following reasons:

(1) Often, presently used switches and relays are relatively complex, bulky and expensive. For example, they are not easily adaptable for use with coaxial cable. Often, to adapt such switches and relays for use with coaxial cable, auxiliary connectors of a complex nature are required.

(2) In order to keep electrical energy reflections small, it is required that tolerances in the machining of parts be closely held. Moreover, these parts must be accurately assembled and aligned.

(3) Many presently used switches and relays require signals of a relatively high power level to operate them. Often, too, such switches and relays do not respond quickly to control signals.

(4) In general, the complexity of many presently used switches and relays tends to promote unreliable switching and transmission functions.

Accordingly, the general objects of this invention include: the provision of a relatively simple, compact and inexpensive relay adaptable for use with coaxial cable transmission lines; the provision of such a relay wherein electrical energy reflections are kept at a minimum; and, the provision of such a relay which responds relatively quick in response to control signals of a relatively low power level.

Among the many kinds of switching devices widely used for the switching of direct currents and low frequency currents is the reed switch, or reed relay. In one of its more common construction forms, the reed relay comprises a pair of cantilever-suspended magnetizable reeds arranged within a hermetically sealed glass envelope; the freely suspended ends of the reeds being situated in spaced-apart, overlapping relationship. When a coil, encompassing the envelope, is energized, the magnetic field introduced into the magnetizable reeds causes the reeds to move into mutual contact due to the forces of magnetic attraction thereby completing an electrical circuit through the reeds. Advantageously, reed relays are relatively simple, compact, reliable and inexpensive components. They respond rather quickly to control signals. Moreover, they may be controlled by signals of a relatively low power level.

Accordingly, a specific object of this invention is to provide a relay, of the reed-relay type, which is particularly suitable for integral coupling with coaxial cable.

Another specific object of this invention is the provision of a reed-type relay having electrical characteristics compatible with the coaxial cable transmission line which it controls; such relay being selectively operable so that the line may be terminated in its characteristic impedance, preventing the translation of high frequency signals through the line; or, in the alternative, to provide conice tinuity along the coaxial cables center conductor to enable translation of high frequency signals.

The following summary will serve to provide an initial appreciation of the general nature of the coaxial relay of this invention:

A reed-type relay is combined with a coaxial cable coupling member; the coaxial cable coupling member comprising: an annular sheath conductor and a discontinuous center conductor comprising two conductor lengths, axially aligned within the annular sheath conductor; such coaxial coupling member being suitable for electrically connecting two coaxial cable lengths. Situated within the sheath conductor and between the two lengths of center conductor is a reed-type switch comprising: a pair of cantilevensuspended magnetizable reeds supported and housed in a hermetically sealed envelope of dielectric material. The supported ends of each reed are connected with a different one of the center conductor lengths to enable continuity therebetween. Supported within the dielectric envelope and protruding therethrough are resistance elements so arranged, with respect to each magnetizable reed, that electrical continuity between each center conductor length and the annular sheath conductor is enabled to allow the coaxial transmission line to be terminated in its characteristic impedance. Scribed, or suitably printed, on the outer surface of the dielectric envelope is a spiral-like electrical path which provides a control coil for operating the reed switch. The coil may also be located external to the outer sheath conductor because the sheath material will not obstruct the magnetic flux lines.

A fuller appreciation of the objects, hereinbefore stated, of this invention will be realized by referring to the following detailed description, and claim, read in connection with the drawings in which:

FIGURE 1 is a perspective view, in section, of the coaxial relay embodying the invention; and,

FIGURE 2 is a perspective view, partly in section, of the dielectric envelope having a control coil integral therewith, employed in the coaxial relay shown at FIG- UR=E 1.

An illustration of one embodiment of the coaxial relay of this invention is provided at FIGURE 1 of the drawing. The coaxial relay, there illustrated, is in its normal status; i.e., the coil 10 is not energized. Accordingly, the two reeds 11 and 12 are biased, by virtue of their alignment and natural strains, to assume the attitudes shown: The reed 1 1 is in contact with the resistive element 13. The reed 12 is in contact with the resistive element 14.

When the coil 10 is energized by applying a potential difference between the coil leads 15 and 16, current passing through the coil creates a magnetic field which is generally oriented along the longitudinal axes of the reeds. Magnetic poles of opposite polarity appear at the freely suspended ends of the reeds; i.e., at the ends 11a and 12a. Consequently, the reeds 11 and 12 are, by the force of magnetic attraction, pulled together thereby causing electrical continuity between the two center conductor lengths 17 and 18.

In its normal status (coil 10 not energized), the reed ends 11a and 12a, respectively, connect the center conductor lengths 17 and 18 through the resistive elements 13 and 14, by means of the leads 19 and 20, to the annular sheath conductor 21, as shown at FIGURE 1 of the drawing. The resistive elements 13 and 14 and the dielectric filler material member 22 may be suitably chosen and proportioned such that the coaxial relay, when in its normal status, functions to terminate a length of coaxial cable in its characteristic impedance. On the other hand, when the coil 10* is energized, the center conductor lengths 17 and 18 are connected through the contacting reeds 11 and 12. Accordingly, a high frequency potential difference, applied between the annular sheath conductor 21 and the center conductor length 17, may be translated through the coaxial relay to a coaxial cable (suggested by the dotted line representation shown at FIGURE 1). The coaxial relay may be integrally coupled, in-line with, the section of coaxial cable, by interconnecting the relays center conductor length 18 and the annular sheath conductor 21 to the coaxial cable by means of a coaxial conneotor suitable for the purpose. Such connectors are well known to those persons skilled in the art. See, for example, chapter 8 of volume 1 of the text Very High- Frequency Techniques, authored by the Radio Research Laboratory Staff of Harvard University and published by the McGraw-Hill Book Company (copyright 1947).

At FIGURE 2 of the drawing, there is illustrated an especially advantageous means for housing, and controlling, the reeds and resistive elements. An envelope 23 has a coil configuration 10 integral therewith. The envelope 23 is a closed tubulation of dielectric material having a coil configuration 10' scribed, suitably printed or otherwise bonded on the outer surface thereof. The coil leads and 16 may be suitably connected to the coil configuration terminations by directly bonding them to the coil terminations. Ways and means of doing this are well known.

The small apertures 24 and 25 ahe provided in the annular sheath conductor 21 for bringing out the leads 15 and 16 to a suitable source of coil potential (not shown). The envelope 23 is fashioned from a suitable dielectric material such as glass, a plastic-like compound, or the like; such material being, advantageously, easily plasticized by the application of heat and, subsequently, cooled to support and seal the reeds and resistive elements therewithin.

Many materials and parts are available for constructing the coaxial relay of this invention. Accordingly, the following materials are to be understood as being illustrative of, not limited to, those which may be employed in constructing the relay of this invention;

Copper, or aluminum, may be used for the coil configuration 10; the coil leads 15 and 16; the center conductor lengths 17 and 18; the leads 19 and 20; and, the annular sheath conductor 21.

The resistive elements 13 and 14 may be fashioned from a ceramic resistance material such as ferrite or from a hardened carbon compound.

The coil 23 may be fashioned from such materials as are hereinbefore set forth.

The dielectric filler material 22 may be polyethylene or the like.

Although one embodiment of the invention has been described and illustrated, it is obvious that many changes, substitutions of elements and materials, as well as arr-angements of parts, may be made without departing from the spirit and scope of the invention as is hereinafter defined in the claim.

What is claimed is:

A coaxial relay, for switching electrical energy containing high frequency components in a coaxial cable transmission line, comprising: an annular sheath of electrically conductive material and a pair of separated center conductors coaxially aligned within the annular sheath conductor, the annular sheath conductor and center conductors being adaptable for integral in-line coupling in a coaxial cable transmission line; an envelope of dielectric material situated between the separated center conductors; a coil configuration of electrically conductive material bonded on the envelopes outer surface; a pair of cantilever-suspended magnetizable reeds sealed Within and protruding through the envelope, each center conductor being connected to a different protruding reed; a pair of resistive elements sealed within and protruding through the envelope; connection means for electrically connecting each resistive element to the annular sheath conductor; and, dielectric material filling the space between the inside surface of the sheath conductor and encompassing the center conductors and envelope; each reed being normally in contact with a different one of the resistive elements whereby the coaxial cable transmission line is terminated in its characteristic impedance.

References Cited in the file of this patent UNITED STATES PATENTS 2,264,124 Schreiner Nov. 25, 1941 2,958,054 Concelman Oct. 25, 1960 2,993,104 Zimmer July 18, 1961 3,019,402 Lanctot Jan. 30, 1962 3,027,524 May Mar. 27, 1962 

